/*
 * Copyright 2012-2023 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.cloud.context.named;

import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

import org.springframework.aot.AotDetector;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactoryUtils;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.ApplicationContextInitializer;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.AnnotationConfigRegistry;
import org.springframework.context.support.GenericApplicationContext;
import org.springframework.core.ResolvableType;
import org.springframework.core.env.MapPropertySource;
import org.springframework.util.Assert;

/**
 * Creates a set of child contexts that allows a set of Specifications to define the beans
 * in each child context.
 * <p>
 * Ported from spring-cloud-netflix FeignClientFactory and SpringClientFactory
 *
 * @param <C> specification
 * @author Spencer Gibb
 * @author Dave Syer
 * @author Tommy Karlsson
 * @author Olga Maciaszek-Sharma
 */
public abstract class NamedContextFactory<C extends NamedContextFactory.Specification>
        implements DisposableBean, ApplicationContextAware {

    private final Map<String, ApplicationContextInitializer<GenericApplicationContext>> applicationContextInitializers;

    private final String propertySourceName;

    private final String propertyName;

    private final Map<String, GenericApplicationContext> contexts = new ConcurrentHashMap<>();

    private final Map<String, C> configurations = new ConcurrentHashMap<>();

    private ApplicationContext parent;

    private final Class<?> defaultConfigType;

    public NamedContextFactory(Class<?> defaultConfigType,
                               String propertySourceName,
                               String propertyName) {
        this(defaultConfigType, propertySourceName, propertyName, new HashMap<>());
    }

    public NamedContextFactory(Class<?> defaultConfigType,
                               String propertySourceName,
                               String propertyName,
                               Map<String, ApplicationContextInitializer<GenericApplicationContext>> applicationContextInitializers) {
        this.defaultConfigType = defaultConfigType;
        this.propertySourceName = propertySourceName;
        this.propertyName = propertyName;
        this.applicationContextInitializers = applicationContextInitializers;
    }

    @Override
    public void setApplicationContext(ApplicationContext parent) throws BeansException {
        this.parent = parent;
    }

    public ApplicationContext getParent() {
        return parent;
    }

    public void setConfigurations(List<C> configurations) {
        for (C client : configurations) {
            this.configurations.put(client.getName(), client);
        }
    }

    public Set<String> getContextNames() {
        return new HashSet<>(this.contexts.keySet());
    }

    @Override
    public void destroy() {
        Collection<GenericApplicationContext> values = this.contexts.values();
        for (GenericApplicationContext context : values) {
            // This can fail, but it never throws an exception (you see stack traces
            // logged as WARN).
            context.close();
        }
        this.contexts.clear();
    }

    protected GenericApplicationContext getContext(String name) {
        if (!this.contexts.containsKey(name)) {
            synchronized (this.contexts) {
                if (!this.contexts.containsKey(name)) {
                    this.contexts.put(name, createContext(name));
                }
            }
        }
        return this.contexts.get(name);
    }

    public GenericApplicationContext createContext(String name) {
        GenericApplicationContext context = buildContext(name);
        // there's an AOT initializer for this context
        if (applicationContextInitializers.get(name) != null) {
            applicationContextInitializers.get(name).initialize(context);
            context.refresh();
            return context;
        }
        registerBeans(name, context);
        context.refresh();
        return context;
    }

    public void registerBeans(String name,
                              GenericApplicationContext context) {
        Assert.isInstanceOf(AnnotationConfigRegistry.class, context);
        AnnotationConfigRegistry registry = (AnnotationConfigRegistry) context;
        if (this.configurations.containsKey(name)) {
            for (Class<?> configuration : this.configurations.get(name).getConfiguration()) {
                registry.register(configuration);
            }
        }
        for (Map.Entry<String, C> entry : this.configurations.entrySet()) {
            if (entry.getKey().startsWith("default.")) {
                for (Class<?> configuration : entry.getValue().getConfiguration()) {
                    registry.register(configuration);
                }
            }
        }
        registry.register(PropertyPlaceholderAutoConfiguration.class, this.defaultConfigType);
    }

    public GenericApplicationContext buildContext(String name) {
        // https://github.com/spring-cloud/spring-cloud-netflix/issues/3101
        // https://github.com/spring-cloud/spring-cloud-openfeign/issues/475
        ClassLoader classLoader = getClass().getClassLoader();
        GenericApplicationContext context;
        if (this.parent != null) {
            DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
            if (parent instanceof ConfigurableApplicationContext) {
                beanFactory.setBeanClassLoader(((ConfigurableApplicationContext) parent).getBeanFactory().getBeanClassLoader());
            } else {
                beanFactory.setBeanClassLoader(classLoader);
            }
            context = AotDetector.useGeneratedArtifacts() ? new GenericApplicationContext(beanFactory) : new AnnotationConfigApplicationContext(beanFactory);
        } else {
            context = AotDetector.useGeneratedArtifacts() ? new GenericApplicationContext() : new AnnotationConfigApplicationContext();
        }
        context.setClassLoader(classLoader);
        context.getEnvironment().getPropertySources().addFirst(new MapPropertySource(this.propertySourceName, Collections.singletonMap(this.propertyName, name)));
        if (this.parent != null) {
            // Uses Environment from parent as well as beans
            context.setParent(this.parent);
        }
        context.setDisplayName(generateDisplayName(name));
        return context;
    }

    protected String generateDisplayName(String name) {
        return this.getClass().getSimpleName() + "-" + name;
    }

    public <T> T getInstance(String name,
                             Class<T> type) {
        GenericApplicationContext context = getContext(name);
        try {
            return context.getBean(type);
        } catch (NoSuchBeanDefinitionException e) {
            // ignore
        }
        return null;
    }

    public <T> ObjectProvider<T> getLazyProvider(String name,
                                                 Class<T> type) {
        return new ClientFactoryObjectProvider<>(this, name, type);
    }

    public <T> ObjectProvider<T> getProvider(String name,
                                             Class<T> type) {
        GenericApplicationContext context = getContext(name);
        return context.getBeanProvider(type);
    }

    public <T> T getInstance(String name,
                             Class<?> clazz,
                             Class<?>... generics) {
        ResolvableType type = ResolvableType.forClassWithGenerics(clazz, generics);
        return getInstance(name, type);
    }

    @SuppressWarnings("unchecked")
    public <T> T getInstance(String name,
                             ResolvableType type) {
        GenericApplicationContext context = getContext(name);
        String[] beanNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(context, type);
        for (String beanName : beanNames) {
            if (context.isTypeMatch(beanName, type)) {
                return (T) context.getBean(beanName);
            }
        }
        return null;
    }

    public <T> Map<String, T> getInstances(String name,
                                           Class<T> type) {
        GenericApplicationContext context = getContext(name);

        return BeanFactoryUtils.beansOfTypeIncludingAncestors(context, type);
    }

    public Map<String, C> getConfigurations() {
        return configurations;
    }

    /**
     * Specification with name and configuration.
     */
    public interface Specification {

        String getName();

        Class<?>[] getConfiguration();

    }

}
